Membrane ruffling plays an important role in the directed cell migration and escape of tumor cells from the monolayer. Metastasis suppressor 1 (MTSS1), also known as missing in metastasis, has been implicated in cell morphology, motility, metastasis, and development. Here, the dynamic interaction proteins associated with MTSS1 and involved in membrane ruffling were determined by cross-linking and mass spectrometry analysis. We identified α-actinin 4 (ACTN4) as an interacting protein and confirmed a direct interaction between MTSS1 and ACTN4. Moreover, co-expression of MTSS1 in fibroblasts recruited cytoplasmic ACTN4 to the cell periphery, at which point ruffling became thick and rigid. In MCF-7 cells, MTSS1 knockdown did not show an obvious effect on the cell shape or the distribution of endogenous ACTN4; however, ACTN4 overexpression transformed cell morphology from an epidermal- to a fibroblast-like shape, and further MTSS1 depletion significantly increased the ratio of fibroblast cells exhibiting prominent ruffling. Furthermore, biochemical data suggested that MTSS1 cross-linking with ACTN4 induced the formation of actin fiber bundles into more organized structures in vitro. These data indicated that MTSS1 might recruit cytoplasmic ACTN4 to the cell periphery and regulate cytoskeleton dynamics to restrict its performance in membrane ruffling.

中文翻译：

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转移抑制因子 1 与 α-actinin 4 相互作用以影响其定位并调节膜皱褶的形成

膜起皱在定向细胞迁移和肿瘤细胞从单层逃逸中起重要作用。转移抑制因子 1 (MTSS1)，也称为转移缺失，与细胞形态、运动、转移和发育有关。在这里，通过交联和质谱分析确定了与 MTSS1 相关并参与膜起皱的动态相互作用蛋白。我们将 α-actinin 4 (ACTN4) 鉴定为一种相互作用蛋白，并证实了 MTSS1 和 ACTN4 之间的直接相互作用。此外，MTSS1 在成纤维细胞中的共表达将细胞质 ACTN4 募集到细胞外围，此时起皱变得厚实和僵硬。在 MCF-7 细胞中，MTSS1 敲低对细胞形状或内源性 ACTN4 的分布没有明显影响；然而，ACTN4 过表达将细胞形态从表皮转变为成纤维细胞样形状，进一步的 MTSS1 消耗显着增加了表现出显着褶皱的成纤维细胞的比例。此外，生化数据表明，MTSS1 与 ACTN4 交联诱导肌动蛋白纤维束在体外形成更有组织的结构。这些数据表明 MTSS1 可能将细胞质 ACTN4 募集到细胞外围并调节细胞骨架动力学以限制其在膜起皱中的表现。生化数据表明，MTSS1 与 ACTN4 交联诱导肌动蛋白纤维束在体外形成更有组织的结构。这些数据表明 MTSS1 可能将细胞质 ACTN4 募集到细胞外围并调节细胞骨架动力学以限制其在膜起皱中的表现。生化数据表明，MTSS1 与 ACTN4 交联诱导肌动蛋白纤维束在体外形成更有组织的结构。这些数据表明 MTSS1 可能将细胞质 ACTN4 募集到细胞外围并调节细胞骨架动力学以限制其在膜起皱中的表现。